Recently, iChEM researchers, Professor Yonggang Wang of Fudan University and his research team used a simple pre-lithiation method to build a Li2V2(PO4)3//LixC lithium-ion battery system, which exhibits high power, long life and good Low temperature performance.

　　Recently, iChEM researchers, Professor Yonggang Wang of Fudan University and his research team used a simple pre-lithiation method to build a Li2V2(PO4)3//LixC lithium-ion battery system, which exhibits high power, long life and good Low temperature performance.

　　In recent years, electric vehicles powered by lithium-ion batteries have been developing rapidly. However, it is well known that the performance of lithium-ion batteries declines rapidly as the temperature decreases. This will greatly limit the application of electric vehicles in winter or some alpine regions.

　　Preliminary studies have shown that in addition to the low ionic conductivity of the electrolyte at low temperatures, the low-temperature performance of conventional lithium-ion batteries based on graphite anodes is also limited by the desolventization/solvation of lithium ions in and out of graphite at low temperatures. In response to this problem, the research group used a pre-lithiated hard carbon negative electrode to replace the traditional graphite negative electrode, and combined with lithium vanadium phosphate (Li2V2(PO4)3) positive electrode to form a new battery system.

　　In recent years, prelithiated hard carbon (Prelithiated hardcarbon) has been applied to hybrid lithium ion capacitors, and has shown excellent electrochemical performance. However, the pre-lithiation process is complicated and costly, which involves the use of pure lithium electrodes, and poses safety risks. In this research, the researchers cleverly used the multi-step delithiation process of Li3V2(PO4)3 cathode material to achieve the prelithiation of hard carbon.

　　In the first charging process, lithium ions are extracted from the positive electrode to form Li2V2(PO4)3, and the extracted lithium ions will be inserted into the hard carbon negative electrode, forming a pre-lithiated hard carbon negative electrode (LixC). Subsequently, Li2V2(PO4)3 and LixC formed a lithium-ion battery system. When charged and discharged at 3.5V and 4.3V, the battery exhibits high power and long life similar to supercapacitors.

　　In addition, although the conventional electrolyte LB303 is used, the battery exhibits excellent low-temperature performance. At minus 40 degrees Celsius, its capacity can maintain 67% of room temperature capacity, far better than conventional lithium-ion batteries. This is mainly due to the good low-temperature performance of the nano-carbon-coated Li2V2(PO4)3 cathode material and the relatively fast kinetic process of the pre-lithiated hard carbon anode at low temperature.

　　However, it is worth noting that the battery system only uses part of the capacity of Li3V2(PO4)3, and the energy density is limited, so it is more suitable for use as a start-stop battery. In addition, as the temperature decreases, the ionic conductance of the electrolyte drops rapidly, which increases the internal resistance of the battery. Therefore, the battery exhibits significant polarization at low temperatures. In follow-up research, it is necessary to further develop high-performance low-temperature electrolytes to improve the electrochemical performance of such batteries at low temperatures.